Content Duration MIME Header Definition
obsoletes
- rfc-2424 — Content Duration MIME Header Definition
Extracted elements (6)
The Content-Duration header allows simple determination of media duration without opening or decoding the content itself. Many encodings include duration internally, but a MIME header provides easy access without processing the binary data.
The time value in Content-Duration should be exact, but the exact value cannot be known without opening and playing the content. This mechanism simply allows placing a sender-determined value in the header; if an exact value is required, the content itself must be examined.
All VPIM Messages MUST contain the audio/32KADPCM sub-type with the Content-Duration header field to carry the audio of a voice message.
The Content-Duration MIME header field specifies the time duration in seconds of time-varying media content (typically audio/* or video/*). The value is a single integer with no units tag.
In some environments, explicitly identifying the time duration of audio/* or video/* content in a header may be a security issue and should not be noted. Reliance on the Content-Duration header cannot be trusted for determining exact data size; the exact length must be determined by examining the data itself.
The Content-Duration field syntax is: `duration := "Content-Duration" ":" 1*10DIGIT`. The value is 1 to 10 decimal digits representing seconds, with a practical upper bound of 2147483647 (2^31 - 1).